<template>
 <div id="home">
   <nav-bar class="home-nav"><div slot="center">购物街</div></nav-bar>
   <tab-control :titles="['流行', '新款', '精选']"
                @tabClick="tabControlClick"
                ref="tabControl1"
                class="tab-control"
                v-show="isTabFixed"/>
    <scroll class="content"
            ref="scroll"
            :probe-type="3"
            @scroll="contentScroll"
            :pull-up-load="true"
            @pullingUp="loadMore">
      <!--此处若不加冒号，则把3当作字符串传入-->
      <home-swiper :banners="banners" @swiperImageLoad="swiperImageLoad"/>
      <recommend-view :recommends="recommends"/>
      <feature-view/>
      <tab-control :titles="['流行', '新款', '精选']"
                   @tabClick="tabControlClick"
                   ref="tabControl2"/>
      <goods-list :goods="showGoods"/>
    </scroll>
   <back-top @click.native="backClick" v-show="isShowBackTop"/>
 </div>
</template>

<script>
  import HomeSwiper from "./childComps/HomeSwiper";
  import RecommendView from "./childComps/RecommendView";
  import FeatureView from "./childComps/FeatureView";

  import NavBar from "components/common/navbar/NavBar";
  import Scroll from "components/common/scroll/Scroll";
  import BackTop from "components/content/backTop/BackTop";
  import TabControl from "components/content/tabControl/TabControl";
  import GoodsList from "components/content/goods/GoodsList";

  import { getHomeMultidata, getHomeGoods } from "network/home";
  import {tabControlMixin, itemImgListenerMixin, backTopMixin} from "common/mixin";

  export default {
    name: "Home",
    components: {
      HomeSwiper,
      RecommendView,
      FeatureView,
      NavBar,
      Scroll,
      BackTop,
      TabControl,
      GoodsList
    },
    mixins: [tabControlMixin, itemImgListenerMixin, backTopMixin],
    data() {
      return {
        banners: [],
        recommends: [],
        goods: {
          'pop': {page: 0, list: []},
          'new': {page: 0, list: []},
          'sell': {page: 0, list: []},
        },
        currentType: 'pop',
        tabOffsetTop: 0,
        isTabFixed: false,
        saveY: 0,
      }
    },
    computed: {
      showGoods() {
        return this.goods[this.currentType].list
      }
    },
    destroyed() {
      console.log('home destroyed');
    },
    activated() {
      // console.log(this.saveY);
      // 第三个参数不能为0，否则会出bug（自动弹回顶部）
      this.$refs.scroll.scrollTo(0, this.saveY, 200);
      // 重新回来时最好刷新一次，否则会出现莫名其妙的问题（eg：弹回顶部）
      this.$refs.scroll.refresh();
    },
    deactivated() {
      // console.log('deactivated');
      // 1.保存Y值
      this.saveY = this.$refs.scroll.getScrollY();

      // 2.取消全局事件的监听
      this.$bus.$off('itemImgLoad', this.itemImgListener);
    },
    created() {
      // 1.请求多个数据
      this.getHomeMultidata();

      // 2.请求商品数据
      this.getHomeGoods('pop');
      this.getHomeGoods('new');
      this.getHomeGoods('sell');
    },
    // mounted() {
    //   // 1.监听item中图片加载完成
    //   // this.$refs.scroll.refresh();
    //   const refresh = debounce(this.$refs.scroll.refresh, 200);
    //
    //   // 对监听的事件进行保存
    //   this.itemImgListener = () => {
    //     refresh();
    //   }
    //   this.$bus.$on('itemImageLoad', this.itemImgListener);
    // },
    methods: {
      // 监听滚动区域滚动了多少距离
      contentScroll(position) {
        // console.log(position);
        // 1.判断BackTop是否显示
        // this.isShowBackTop = -position.y > 1000
        this.listenShowBackTop(position);

        // 2.决定tabControl是否吸顶
        this.isTabFixed = (-position.y) > this.tabOffsetTop
      },

      loadMore() {
        this.getHomeGoods(this.currentType);
      },

      swiperImageLoad() {
        // 1.获取tabControl2的offsetTop
        // 所有的组件都有一个属性$el：用于获取组件中的元素
        this.tabOffsetTop = this.$refs.tabControl2.$el.offsetTop;
      },

      // 网络请求相关的方法
      getHomeMultidata() {
        getHomeMultidata().then(res => {
          // console.log(res);
          this.banners = res.data.banner.list;
          this.recommends = res.data.recommend.list;
        })
      },
      getHomeGoods(type) {
        const page = this.goods[type].page + 1;
        getHomeGoods(type, page).then(res => {
          this.goods[type].list.push(...res.data.list);
          this.goods[type].page += 1;

          // 完成上拉加载更多
          this.$refs.scroll.finishPullUp();
        })
      },
    }
  }
</script>

<!--scoped属性限制了此处样式作用的范围仅在本组件-->
<style scoped>
  #home {
    /*padding-top: 44px;*/
    /*视口高度为100%*/
    height: 100vh;
    position: relative;
  }

  .home-nav {
    background-color: var(--color-tint);
    color: #fff;

    /*在使用浏览器原生滚动时，为了让导航不跟随一起滚动*/
    /*position: fixed;*/
    /*left: 0;*/
    /*right: 0;*/
    /*top: 0;*/
    /*z-index: 9;*/
  }

  .content {
    position: absolute;
    top: 44px;
    bottom: 49px;
    left: 0;
    right: 0;
    overflow: hidden;
  }

  .tab-control {
    position: relative;
    z-index: 9;
  }

  /*.content {*/
  /*  height: calc(100% - 93px);*/
  /*  overflow: hidden;*/
  /*  !*margin-top: 44px;*!*/
  /*}*/
</style>
